已知等差数列an的前n项和为sn,且满足a2+a4=6 s7=28
已知等差数列{an}的前n项和为Sn,且满足:a2+a4=14,S7=70.
已知等差数列{an}的前n项和为Sn,且满足a2+a4=14,S7=70
已知等差数列an的前n项和为Sn,且满足a2+a4=14,S7=70
已知等差数列an的前n项和为Sn,且满足a2+a4=14,S7=70.求数列an的通项公式
已知等差数列{an}的前n项和为Sn,且满足:a2+a4=6,S7=28,求数列的通项公式
sn为等差数列an的前n项和 已知S3/S7=2/5 则a2/a4
已知Sn为等差数列{an}的前n项和,若a2:a4=7:6,则S7:S3等于______.
等差数列{An}的前n项和为Sn,且满足A3*A4=117,A2+A5=22 求通项An ;若数列{Bn}是等差数列,且
已知公差大于零的等差数列{an}的前n项和为Sn,且满足:a3•a4=117,a2+a5=22.
已知公差大于零的等差数列{an}的前n项和为Sn,且满足:a3*a4=117,a2+a5=22
已知公差数列大于零的等差数列{an}的前n项和为Sn,且满足a3*a4=117,a2+a5=22
等差数列{an}的前n项和为Sn,若a2+a4+a6=12,则S7的值是______.